In a recent energy saving trend, there has been an increasing demand for improving the performance of an air blower of an air conditioner. The performance of an air blower is enhanced by improving the flow characteristic of the air passage in which the air blower is arranged, and by reducing the noise level.
In order to respond to the demand, in the conventional air conditioner, the performance of the air blower is improved by expanding the suction port of the air passage and by increasing the minimum distance between the stabilizer and the rear guider which are respectively arranged on the front and rear sides of the cross flow fan configuring the air blower.
However, with such means, the performance of the air blower can be improved, but the air blower becomes a low static pressure type. For this reason, there is a problem that, when a large amount of dust and dirt adhere to the air filter arranged at the suction port in actual use, that is, during high dust load, the amount of air blown out from the blowout port is not stabilized, and thereby the air flow characteristics are deteriorated.
Further, the air conditioner provided with the cross flow fan has a characteristic that, when a load is applied to the cross flow fan, in the vicinity of the side wall of each of the left and right ends of the blowout port, the flow of blown out air tends to become unstable due to the influence of the resistance of the side wall, and to generate abnormal “flapping” sound which also becomes the cause of the noise.
In order to solve the above described problem, Patent Literature 1 proposes a structure in which a protrusion is formed to extend in the vicinity of the side wall of each of the left and right end sections of the blowout port, and thereby the peeled flow of air blown out along the rear guider is smoothed so as to reduce noise.
Further, Patent Literature 1 proposes another form that is configured to reduce noise in such a manner that a protrusion having a two-stage level difference along the air flow direction of the air passage is provided at each of the side walls in the downstream area of the cross flow fan, and thereby the width of the air passage sectional area, which is expanded in the rotating shaft direction of the cross flow fan from the upstream side to the downstream side of air flow, is reduced by the two-stage level difference, so as to reduce the variation components of the air passage in the rotating shaft direction to smooth the flow of blown out air.